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[Xen-devel] [PATCH] x86/hvm: miscellaneous CPUID handling changes



- use __clear_bit() rather than clear_bit()
- use switch statements instead of long series of if-s
- eliminate pointless casts

(Applies cleanly only on top of the previously sent SVM/EFER patch.)

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

Index: 2007-08-08/xen/arch/x86/hvm/hvm.c
===================================================================
--- 2007-08-08.orig/xen/arch/x86/hvm/hvm.c      2007-08-06 15:08:40.000000000 
+0200
+++ 2007-08-08/xen/arch/x86/hvm/hvm.c   2007-08-08 11:45:25.000000000 +0200
@@ -614,37 +614,38 @@ void hvm_cpuid(unsigned int input, unsig
 {
     if ( !cpuid_hypervisor_leaves(input, eax, ebx, ecx, edx) )
     {
+        struct vcpu *v = current;
+
         cpuid(input, eax, ebx, ecx, edx);
 
-        if ( input == 0x00000001 )
+        switch ( input )
         {
-            struct vcpu *v = current;
-
-            clear_bit(X86_FEATURE_MWAIT & 31, ecx);
+        case 0x00000001:
+            __clear_bit(X86_FEATURE_MWAIT & 31, ecx);
 
             if ( vlapic_hw_disabled(vcpu_vlapic(v)) )
-                clear_bit(X86_FEATURE_APIC & 31, edx);
+                __clear_bit(X86_FEATURE_APIC & 31, edx);
 
 #if CONFIG_PAGING_LEVELS >= 3
             if ( !v->domain->arch.hvm_domain.params[HVM_PARAM_PAE_ENABLED] )
 #endif
-                clear_bit(X86_FEATURE_PAE & 31, edx);
-            clear_bit(X86_FEATURE_PSE36 & 31, edx);
-        }
-        else if ( input == 0x80000001 )
-        {
+                __clear_bit(X86_FEATURE_PAE & 31, edx);
+            __clear_bit(X86_FEATURE_PSE36 & 31, edx);
+            break;
+
+        case 0x80000001:
 #if CONFIG_PAGING_LEVELS >= 3
-            struct vcpu *v = current;
             if ( !v->domain->arch.hvm_domain.params[HVM_PARAM_PAE_ENABLED] )
 #endif
-                clear_bit(X86_FEATURE_NX & 31, edx);
+                __clear_bit(X86_FEATURE_NX & 31, edx);
 #ifdef __i386__
             /* Mask feature for Intel ia32e or AMD long mode. */
-            clear_bit(X86_FEATURE_LAHF_LM & 31, ecx);
+            __clear_bit(X86_FEATURE_LAHF_LM & 31, ecx);
 
-            clear_bit(X86_FEATURE_LM & 31, edx);
-            clear_bit(X86_FEATURE_SYSCALL & 31, edx);
+            __clear_bit(X86_FEATURE_LM & 31, edx);
+            __clear_bit(X86_FEATURE_SYSCALL & 31, edx);
 #endif
+            break;
         }
     }
 }
Index: 2007-08-08/xen/arch/x86/hvm/svm/svm.c
===================================================================
--- 2007-08-08.orig/xen/arch/x86/hvm/svm/svm.c  2007-08-08 11:43:53.000000000 
+0200
+++ 2007-08-08/xen/arch/x86/hvm/svm/svm.c       2007-08-08 11:45:25.000000000 
+0200
@@ -1117,8 +1117,9 @@ static void svm_vmexit_do_cpuid(struct v
 
     hvm_cpuid(input, &eax, &ebx, &ecx, &edx);
 
-    if ( input == 0x00000001 )
+    switch ( input )
     {
+    case 0x00000001:
         /* Clear out reserved bits. */
         ecx &= ~SVM_VCPU_CPUID_L1_ECX_RESERVED;
         edx &= ~SVM_VCPU_CPUID_L1_EDX_RESERVED;
@@ -1126,50 +1127,56 @@ static void svm_vmexit_do_cpuid(struct v
         /* Guest should only see one logical processor.
          * See details on page 23 of AMD CPUID Specification.
          */
-        clear_bit(X86_FEATURE_HT & 31, &edx);  /* clear the hyperthread bit */
+        __clear_bit(X86_FEATURE_HT & 31, &edx);  /* clear the hyperthread bit 
*/
         ebx &= 0xFF00FFFF;  /* clear the logical processor count when HTT=0 */
         ebx |= 0x00010000;  /* set to 1 just for precaution */
-    }
-    else if ( input == 0x80000001 )
-    {
+        break;
+
+    case 0x80000001:
         if ( vlapic_hw_disabled(vcpu_vlapic(v)) )
-            clear_bit(X86_FEATURE_APIC & 31, &edx);
+            __clear_bit(X86_FEATURE_APIC & 31, &edx);
 
 #if CONFIG_PAGING_LEVELS >= 3
         if ( !v->domain->arch.hvm_domain.params[HVM_PARAM_PAE_ENABLED] )
 #endif
-            clear_bit(X86_FEATURE_PAE & 31, &edx);
+            __clear_bit(X86_FEATURE_PAE & 31, &edx);
 
-        clear_bit(X86_FEATURE_PSE36 & 31, &edx);
+        __clear_bit(X86_FEATURE_PSE36 & 31, &edx);
 
         /* Clear the Cmp_Legacy bit
          * This bit is supposed to be zero when HTT = 0.
          * See details on page 23 of AMD CPUID Specification.
          */
-        clear_bit(X86_FEATURE_CMP_LEGACY & 31, &ecx);
+        __clear_bit(X86_FEATURE_CMP_LEGACY & 31, &ecx);
 
         /* Make SVM feature invisible to the guest. */
-        clear_bit(X86_FEATURE_SVME & 31, &ecx);
+        __clear_bit(X86_FEATURE_SVME & 31, &ecx);
+        __clear_bit(X86_FEATURE_SKINIT & 31, &ecx);
+
+        __clear_bit(X86_FEATURE_OSVW & 31, &ecx);
+        __clear_bit(X86_FEATURE_WDT & 31, &ecx);
 
         /* So far, we do not support 3DNow for the guest. */
-        clear_bit(X86_FEATURE_3DNOW & 31, &edx);
-        clear_bit(X86_FEATURE_3DNOWEXT & 31, &edx);
-    }
-    else if ( input == 0x80000007 || input == 0x8000000A )
-    {
+        __clear_bit(X86_FEATURE_3DNOW & 31, &edx);
+        __clear_bit(X86_FEATURE_3DNOWEXT & 31, &edx);
+        break;
+
+    case 0x80000007:
+    case 0x8000000A:
         /* Mask out features of power management and SVM extension. */
         eax = ebx = ecx = edx = 0;
-    }
-    else if ( input == 0x80000008 )
-    {
+        break;
+
+    case 0x80000008:
         /* Make sure Number of CPU core is 1 when HTT=0 */
         ecx &= 0xFFFFFF00;
+        break;
     }
 
-    regs->eax = (unsigned long)eax;
-    regs->ebx = (unsigned long)ebx;
-    regs->ecx = (unsigned long)ecx;
-    regs->edx = (unsigned long)edx;
+    regs->eax = eax;
+    regs->ebx = ebx;
+    regs->ecx = ecx;
+    regs->edx = edx;
 
     HVMTRACE_3D(CPUID, v, input,
                 ((uint64_t)eax << 32) | ebx, ((uint64_t)ecx << 32) | edx);
Index: 2007-08-08/xen/arch/x86/hvm/vmx/vmx.c
===================================================================
--- 2007-08-08.orig/xen/arch/x86/hvm/vmx/vmx.c  2007-08-07 15:00:27.000000000 
+0200
+++ 2007-08-08/xen/arch/x86/hvm/vmx/vmx.c       2007-08-08 11:45:25.000000000 
+0200
@@ -1326,15 +1326,9 @@ static void vmx_do_no_device_fault(void)
 static void vmx_do_cpuid(struct cpu_user_regs *regs)
 {
     unsigned int input = (unsigned int)regs->eax;
-    unsigned int count = (unsigned int)regs->ecx;
     unsigned int eax, ebx, ecx, edx;
 
-    if ( input == 0x00000004 )
-    {
-        cpuid_count(input, count, &eax, &ebx, &ecx, &edx);
-        eax &= NUM_CORES_RESET_MASK;
-    }
-    else if ( input == 0x40000003 )
+    if ( input == 0x40000003 )
     {
         /*
          * NB. Unsupported interface for private use of VMXASSIST only.
@@ -1360,37 +1354,52 @@ static void vmx_do_cpuid(struct cpu_user
         unmap_domain_page(p);
 
         gdprintk(XENLOG_INFO, "Output value is 0x%"PRIx64".\n", value);
-        ecx = (u32)value;
-        edx = (u32)(value >> 32);
-    } else {
-        hvm_cpuid(input, &eax, &ebx, &ecx, &edx);
+        regs->ecx = (u32)value;
+        regs->edx = (u32)(value >> 32);
+        return;
+    }
 
-        if ( input == 0x00000001 )
-        {
-            /* Mask off reserved bits. */
-            ecx &= ~VMX_VCPU_CPUID_L1_ECX_RESERVED;
+    hvm_cpuid(input, &eax, &ebx, &ecx, &edx);
 
-            ebx &= NUM_THREADS_RESET_MASK;
+    switch ( input )
+    {
+    case 0x00000001:
+        /* Mask off reserved bits. */
+        ecx &= ~VMX_VCPU_CPUID_L1_ECX_RESERVED;
 
-            /* Unsupportable for virtualised CPUs. */
-            ecx &= ~(bitmaskof(X86_FEATURE_VMXE) |
-                     bitmaskof(X86_FEATURE_EST)  |
-                     bitmaskof(X86_FEATURE_TM2)  |
-                     bitmaskof(X86_FEATURE_CID));
+        ebx &= NUM_THREADS_RESET_MASK;
 
-            edx &= ~(bitmaskof(X86_FEATURE_HT)   |
-                     bitmaskof(X86_FEATURE_ACPI) |
-                     bitmaskof(X86_FEATURE_ACC));
-        }
+        /* Unsupportable for virtualised CPUs. */
+        ecx &= ~(bitmaskof(X86_FEATURE_VMXE) |
+                 bitmaskof(X86_FEATURE_EST)  |
+                 bitmaskof(X86_FEATURE_TM2)  |
+                 bitmaskof(X86_FEATURE_CID));
 
-        if ( input == 0x00000006 || input == 0x00000009 || input == 0x0000000A 
)
-            eax = ebx = ecx = edx = 0x0;
+        edx &= ~(bitmaskof(X86_FEATURE_HT)   |
+                 bitmaskof(X86_FEATURE_ACPI) |
+                 bitmaskof(X86_FEATURE_ACC));
+
+        /* Unsupported for virtualised CPUs. */
+        ecx &= ~(bitmaskof(X86_FEATURE_PDCM));
+
+        break;
+
+    case 0x00000004:
+        cpuid_count(input, regs->ecx, &eax, &ebx, &ecx, &edx);
+        eax &= NUM_CORES_RESET_MASK;
+        break;
+
+    case 0x00000006:
+    case 0x00000009:
+    case 0x0000000A:
+        eax = ebx = ecx = edx = 0;
+        break;
     }
 
-    regs->eax = (unsigned long)eax;
-    regs->ebx = (unsigned long)ebx;
-    regs->ecx = (unsigned long)ecx;
-    regs->edx = (unsigned long)edx;
+    regs->eax = eax;
+    regs->ebx = ebx;
+    regs->ecx = ecx;
+    regs->edx = edx;
 
     HVMTRACE_3D(CPUID, current, input,
                 ((uint64_t)eax << 32) | ebx, ((uint64_t)ecx << 32) | edx);
Index: 2007-08-08/xen/include/asm-x86/cpufeature.h
===================================================================
--- 2007-08-08.orig/xen/include/asm-x86/cpufeature.h    2007-08-08 
11:45:13.000000000 +0200
+++ 2007-08-08/xen/include/asm-x86/cpufeature.h 2007-08-08 11:45:25.000000000 
+0200
@@ -80,9 +80,15 @@
 #define X86_FEATURE_VMXE       (4*32+ 5) /* Virtual Machine Extensions */
 #define X86_FEATURE_EST                (4*32+ 7) /* Enhanced SpeedStep */
 #define X86_FEATURE_TM2                (4*32+ 8) /* Thermal Monitor 2 */
+#define X86_FEATURE_SSSE3      (4*32+ 9) /* Supplemental Streaming SIMD 
Extensions-3 */
 #define X86_FEATURE_CID                (4*32+10) /* Context ID */
 #define X86_FEATURE_CX16        (4*32+13) /* CMPXCHG16B */
 #define X86_FEATURE_XTPR       (4*32+14) /* Send Task Priority Messages */
+#define X86_FEATURE_PDCM       (4*32+15) /* Perf/Debug Capability MSR */
+#define X86_FEATURE_DCA                (4*32+18) /* Direct Cache Access */
+#define X86_FEATURE_SSE4_1     (4*32+19) /* Streaming SIMD Extensions 4.1 */
+#define X86_FEATURE_SSE4_2     (4*32+20) /* Streaming SIMD Extensions 4.2 */
+#define X86_FEATURE_POPCNT     (4*32+23) /* POPCNT instruction */
 
 /* VIA/Cyrix/Centaur-defined CPU features, CPUID level 0xC0000001, word 5 */
 #define X86_FEATURE_XSTORE     (5*32+ 2) /* on-CPU RNG present (xstore insn) */
@@ -94,6 +100,15 @@
 #define X86_FEATURE_LAHF_LM    (6*32+ 0) /* LAHF/SAHF in long mode */
 #define X86_FEATURE_CMP_LEGACY (6*32+ 1) /* If yes HyperThreading not valid */
 #define X86_FEATURE_SVME        (6*32+ 2) /* Secure Virtual Machine */
+#define X86_FEATURE_EXTAPICSPACE (6*32+ 3) /* Extended APIC space */
+#define X86_FEATURE_ALTMOVCR   (6*32+ 4) /* LOCK MOV CR accesses CR+8 */
+#define X86_FEATURE_ABM                (6*32+ 5) /* Advanced Bit Manipulation 
*/
+#define X86_FEATURE_SSE4A      (6*32+ 6) /* AMD Streaming SIMD Extensions-4a */
+#define X86_FEATURE_MISALIGNSSE        (6*32+ 7) /* Misaligned SSE Access */
+#define X86_FEATURE_3DNOWPF    (6*32+ 8) /* 3DNow! Prefetch */
+#define X86_FEATURE_OSVW       (6*32+ 9) /* OS Visible Workaround */
+#define X86_FEATURE_SKINIT     (6*32+ 12) /* SKINIT, STGI/CLGI, DEV */
+#define X86_FEATURE_WDT                (6*32+ 13) /* Watchdog Timer */
 
 #define cpu_has(c, bit)                test_bit(bit, (c)->x86_capability)
 #define boot_cpu_has(bit)      test_bit(bit, boot_cpu_data.x86_capability)



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